Chakras are the seven basic "energy centers" in specific areas of the spine that correspond with the endocrine glands in the same general vicinity. This is, anatomically speaking, true. Chakras are circular centers of energy which exist in a more subtle realm, and each chakra is connected to a form of human experience/behavior. How one responds to that experience determines the level of involvement of a specific chakra. Or if someone has pain in a certain part of the body, figure out which chakra that area is associated with, then pain can be reduced by practicing yoga poses that enhance that chakra.
The thymus gland corresponds to the heart chakra, number four, on the chakral ladder. It’s also called the anahata chakra, meaning the “un-stuck” chakra. “Un-stuck” in the sense that when the subtle energy rises from the root chakra, corresponding to the base of the spine, to the heart chakra, this energy moves from the physical to the spiritual. Sort of like the gateway from the physical to the spiritual. People tend to stay in the physical, and this "un-stuck-ness" is a powerful move to bring a person to realize the true self, as opposed to the ego self, and rise to a higher level of being. However, it is not a permanent condition. One can go up and down on that chakral ladder for years before becoming fully "un-stuck". Getting in touch with and staying in touch with that true self can be miles apart.
Except, of course, if you’re a kid. On the more subtle level the heart chakra is associated with touch, compassion, empathy and love. Places that adults have a hard time being “un-stuck”. Places where kids tend to roam freely.
Kids pretty much live and exist right from the heart. There’s an actual biological explanation for this. The thymus gland (associated with the heart chakra) located behind the pericardium is most active between birth and puberty. Medical studies indicate it plays a major role in immune defenses of the body as it grows larger during the early years of childhood. Hormones associated with puberty diminish the activity of the thymus, taking over some of its functions, and the thymus gland starts to shrink after puberty and, eventually, becomes adipose (fat) tissue. As a kid reaches puberty, the heart becomes somewhat confused. The emboldened, sure heart of the child becomes the apprehensive, unsure heart of the teenager. Many times the heart of the adult will close completely, and posture can reveal this closing of the heart, a step on the way to kyphosis.
So the journey back to the heart becomes a tangled theme throughout the adult life. Sidetracked by cultural expectations and conventional wisdom, a lot of people forget who they really are/were, and end up talking about the child within like he or she is someone imprisoned or a long-ago friend, often fearful of shedding light on this clue to the true self. Illuminating that child within can be difficult sometimes, but as difficult journeys go, this one is worth it. Just like the physical illnesses for which the thymus gland provides immunity in children, so it may provide immunity for mental or emotional pain during childhood. Facing that pain can be the difficult-but-rewarding journey. Amazingly, correct posture can help begin the journey.
There is a real sense to the phrase “opening the heart chakra” that so many yoga teachers talk about, for opening that place in the body not only corrects posture and aids in correct alignment but can begin the way back to the true self, working through that "stuck-ness". Try this: Roll up a blanket or yoga mat and place the rolled blanket or mat on the floor. Then lie down on the blanket, so that the spine and head are supported by that rolled blanket. The shoulders and the ribs relax back towards the floor, unsupported. Focus on allowing the shoulders to release backwards to the floor, using the exhale to relax and release the muscles at the back of the body. Notice where the body fights the release. Notice tension releasing from the chest. This gives a real physical sense of opening the chest, the heart. Perhaps it gives a subtle sense of empowerment.
Other positions of the body that are said to open the heart and enhance the immune system, concepts in yoga that are, incidentally, deeply connected are cobra, bow pose, fish pose, wheel, singing and chanting, and as Reader’s Digest has always told us and modern medicine is just now catching up to, laughter.